Oncogenicity of Epstein-Barr virus (EBV) will be studied by biochemical methods. Complementary RNA hybridization (cRNA hybridization) and DNA-DNA reassociation kinetics will be used throughout the studies to detect viral genomes. Latency of EBV genomes in Raji cells (50 genomes per cell) and #9 cells (one viral genome per cell) will be studied in regards to integration of any EBV genome into cellular DNA and location of non-integrated EBV DNA in chromatin body. EBV transcription studies will be done in infected or superinfected cells and transformed cells to determine how much of the viral DNA is transcribed, the common species of transcribed RNA both in infected and transformed cells and whether any post transcriptional control can be seen. A physical map of DNA fragments obtained by restriction enzymes will be constructed and biological functions will be assigned to each fragment. Cell and virus mutants will be isolated to improve EBV infection and assay system and to establish permissive infection of EBV.